Motor Cranks but Won't Start - Electrical Problem -

[Kenny]

After about a month sitting in the garage, my EB won't start. It cranks, but I can't get it to fire. Checked my Jacobs Coil and found no spark. I had a spare Jacobs Coil sitting around so I decided to switch. Here's what happened:

When I started cranking with the second coil, it fired for a very quick moment and died. This is the first and last time that I've had any sign of spark since the problem. I'm not sure if two bad coils is just a coincidence, but now I'm worried that I might have an electrical problem that is frying my coils or something else? So here are my questions:

- Anyone know of something that might cause a coil to fry?
- Could a bad Unilite Ignition Module cause the coil to not spark?
- Anything else that you can think of that is causing my lack of spark?

My Bronco specs are 302, stock carb, Jacobs Mileage Master Ignition System (Ultra Coil & Box) and Mallory Unilite Distributor with ballast resistor. I've had trouble free starts for the past eight years with this setup.

What sucks most is that Jacobs Coils and Unilite Ignition modules are not cheap.......if one or the other is fried, don't want to keep burning them up.....need to fix electrical problem if there is one.

Thanks

 

[broncnaz]

It is possible to fry the coils but the unilites are famous for taking a dump. I'd lean more towards that than either coil you will also want to check to make sure you have power going to the coil should be around 8-9 volts I believe could have a bad wire or the contacts in the ignition switch are bad.

 

[BoltBuster]

You may have also fouled the plugs with fuel no spark. (For waht ever the reason the coil stopped firing, Think also lose ground in this case, might not be the coil)

 

[Skuzzlebutt]

Jacobs coils have a reputation for being short lived

 

[RRRAAAYYY2]

When things sit they corrode. Don't know enough about ignitions to go further than that. I would be cleaning everything that is fore sure.

 

[meckanik]

Kenny, ignition coils in general are pretty reliable as they are usually completely potted (set in an epoxy-like mixture). Jacobs ignition module are somewhat notorious for being flakey however (as well as the Ford ones, but they will usually begin to show signs of failure when hot).

You should be able to remove the Jacobs ignition pack from the ignition system and revert to just the factory ignition module. If you still don't have spark things to check:

Take a volt meter (or a test light if you don't own a multimeter) and check for 12V at at the coil with the key on (one of the two wires going to the coil). If you're using a test light the bulb should be as bright going from ground to the positive lead on the coil as it is across the battery terminals.

The next step would be to remove the ignition module and have it tested - any parts store should be able to do this (I reccommend NAPA! )

There is also a pickup in the distributor but this is the last thing that I would inspect in your troubleshooting routine. The distributors and coils are often replaced but don't go bad very often. The Jacobs module would be the first thing to eliminate and then the factory ignition module.

Let us know how it turns out.

-Jeff

 

[Kenny]

I feel kind of stupid, because it ended up being a bad connection to my Unilite Ignition Module.

What threw me off was that the second coil fired for a quick moment then nothing....made me think my coils were frying. Anyway, I had access to another ignition module so I tried it just in case, and my Bronco fired right up. Right before ordering a new Unilite Ignition Module, I noticed a slightly loose connection. Since I don't own a set of good crimpers, I soldered everything up and problem solved. Glad I caught it....saved myself $89 (Summit price)!

Thanks for all of the suggestions! They'll definitely come in handy if/when I come into future electrical problems....